Back pain intensity increases with weight, study finds

PHILADELPHIA — Overweight people with lower back pain is more intense than people of normal weight with back pain, according to a recent study published in the Sept. 15 issue of Spine.

The study sets up another comorbidity associated with being overweight.

The results showed that heavier people had higher levels of back pain intensity. For each five-unit increase in body mass index — equivalent to the difference between being classified as overweight or obese — the odds of high-intensity back pain increased by 35%. For back pain disability, the association was even stronger: 66% per five-unit increase in BMI.

However, the increase in back pain at higher BMIs was specifically related to increased fat mass. For each 11 pounds increase in body fat mass, the odds of high-intensity back pain increased by 19%. For increased fat mass in the lower limbs, the increase was 51%. In contrast, lean body mass was unrelated to back pain. Thus, the increase in back pain intensity among people with higher BMIs was wholly related to their higher body fat content — not just the fact that they were heavier. People with higher body fat also had increased disability from back pain.

The study included 135 participants, ranging from normal weight to obese. All completed a standard questionnaire to measure low back pain intensity and related disability. They also underwent a test called dual-energy X-ray absorptiometry for detailed assessment of body composition, including measurement of fat and lean body mass.